fix: handle lost+found directory in plugin scanner

Signed-off-by: Beth Griggs <bethanyngriggs@gmail.com>

.changeset/smart-avocados-invent.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-dynamic-feature-service': patch
+---
+
+Updates the `scanRoot` method in the `PluginScanner` class to specifically ignore the `lost+found` directory, which is a system-generated directory used for file recovery on Unix-like systems. Skipping this directory avoids unnecessary errors.

packages/backend-dynamic-feature-service/src/scanner/plugin-scanner.test.ts

@@ -636,6 +636,24 @@ Please add '${mockDir.resolve(
           ],
         },
       },
+      {
+        name: 'lost+found directory should be ignored',
+        fileSystem: {
+          backstageRoot: {
+            'dist-dynamic': {
+              'lost+found': {},
+            },
+          },
+        },
+        expectedPluginPackages: [],
+        expectedLogs: {
+          debugs: [
+            {
+              message: `skipping 'lost+found' system directory`,
+            },
+          ],
+        },
+      },
     ])('$name', async (tc: TestCase): Promise<void> => {
       const logger = new MockedLogger();
       const backstageRoot = mockDir.resolve('backstageRoot');

packages/backend-dynamic-feature-service/src/scanner/plugin-scanner.ts

@@ -136,6 +136,11 @@ export class PluginScanner {
       withFileTypes: true,
     })) {
       const pluginDir = dirEnt;
+
+      if (pluginDir.name === 'lost+found') {
+        this.logger.debug(`skipping '${pluginDir.name}' system directory`);
+        continue;
+      }
       const pluginHome = path.normalize(
         path.resolve(dynamicPluginsLocation, pluginDir.name),
       );